The effective velocity model: An improved approach to velocity sampling in actuator line models

Actuator line modeling of wind turbines requires the definition of a free-stream velocity in a computational mesh and a regularization kernel to project the computed body forces onto the domain. Both choices strongly influence the results. In this work, a novel velocity sampling method—the so-called effective velocity model (EVM)—is...

Numerical Investigation of Floating Wind Turbine Wake Interactions Using LES-AL Technique

Large scale wind farms consisting with floating offshore wind turbines (FOWTs) will be a solution for offshore wind energy industry to access more wind resources. However, wake structures and wake interactions of FOWTs subject to motions are still not yet been fully understand, especially when they are under turbulent inflow conditions with...

Numerical Study on the Occurrence and Sensitivity of a High-Frequency Instability in an Advanced Can-Annular Combustion System

Gas turbines for power generation use lean premixed flames to adhere to the strict pollutant emissions regulations. Unfortunately, this often leads to thermoacoustic instabilities. These instabilities can lead to failure of system components, flame blow-off or flashback and a reduction in efficiency. Especially the high frequency transverse...

Numerical Study on the Driving and Damping of High-Frequency Instabilities in a Jet Flame Combustor

Lean premixed flames are being used in gas turbines to reduce the emission of NOx. Unfortunately, it results often in thermoacoustic instabilities. These instabilities are high amplitude pressure oscillations which cause damage to the combustion system, reduce efficiency, flame blow-off or flashback. While the cause for instabilities due to...

Evaluation of a wind farm parameterization in an operational mesoscale model

In the coming decade, the Dutch government plans to broadly expand its wind farm real estate over the North Sea region. This is a significant undertaking because, from literature, it is understood that wind turbines can affect the local environment. These impacts include, but are not limited to, changes in variables such as wind speed and...

Integrating Scanning Lidar with LES for Wake Characterization in Complex Terrain

Flows over complex terrains present uncertainties in wind farm power production and lifespan. Core to these uncertainties are wake dynamics, which lack adequate models and need further validation. In lieu of conducting field experiments, this study integrates scanning lidar measurements and large eddy simulation (LES) to characterize wakes in...

Investigating the performance of wind farms with alternating tower heights

Johnstone and Coleman (2012) were among the first to opt the idea of wind farms with mixed tower heights and predicted an increased power production due to the decrease of losses to TKE production from the mean kinetic energy balance. In the current study, the performance of infinite wind farms with alternating tower heights imposed by a...